1. Field of the Invention
The present invention relates generally to a locking assembly for fastening two fluid-transmitting conduits, and more specifically to an improved, self-locking fluid coupling assembly that does not require utilization of a lock wire or other externally-applied devices or chemical compositions.
2. Background
Fluid-transmitting conduits are used for a variety of purposes in the art. Adjacent conduits are coupled mechanically to allow fluid to flow through both conduits. This coupling is typically accomplished by utilizing a threaded coupling, with each respective end of a conduit is attached to a component of the threaded coupling. The seals of the coupling apparatus are preloaded by making up the threaded connection between the components of the coupling. It is well known in the art that stress, vibration, movement, flexing, and other cyclical or dynamic forces can cause a loosening of a coupled connection, resulting in the release of a desired sealing torque in the connection. This release of torque can result in leaks, a drop in pressure, and other undesirable effects.
Loosening of a fluid-transmitting connection can be a particular problem for pneumatic and hydraulic connectors. These connectors are subject not only to the external forces and stresses identified above, but are also subjected to internal pressure stresses from the fluid being conducted through the coupling. Numerous approaches to addressing these problems exist in the art, including the use of adhesive materials and lock wires to prevent loosening of the coupling. In the aircraft industry, for example, many fluid coupling joints have included compression fittings secured with threaded connections, where a nut is lock-wired to a mating connecting component such that the nut cannot turn with respect to the fitting. This ensures against loss of fluid tightness in the fitting joint. Fluid coupling joints are, however, often assembled in areas where a worker's vision is obscured and the joint assembly occurs outside of the direct vision of the worker. In such cases, use of a lock wire is unsatisfactory. Further, the ability to inspect the assembled joint in order to ascertain the integrity of the joint is also compromised. Thus, lock wires are not suitable means of ensuring a proper connection in all cases. Further, the use of lock wires is a time-consuming process. Typically, a worker has to drill a hole in one or more corners of the nut and secure the wire to a boss or other tie-down structure in order to secure the tie wire. The lock-wired connection can also cause damage to equipment and injury to workers and other personnel because of the twisted wires, which can easily snag on clothing, equipment, or skin.
Other attempts have been made to secure such couplings without the use of lock wires. Many such means of securing the coupling require multiple parts, or complicated parts, to achieve the proper locking of the connection. Some require a lock between the connector and the B-nut (the nut typically used in hydraulic and pneumatic applications), and the connector length is often increased to incorporate the locking features. The increased length of the connector results in an increased weight of the connector, and both the increased weight and length can be problematic in installation, where space is limited. In addition, some of these lockwireless couplings require a specific type or ferrule to be used with the coupling for the locking mechanism to engage.